PHP - isset should be used to see if variable exists, also variable indexes and the like.
ie: isset(myObj['testExist'])); will return true if testExist exists and is non-null

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Chrome and Safari (guessing it's a webkit issue) won't keep the text selected if you just use an onFocus callback with a text.select() call. You must cancel the mouseup event otherwise the text most of the time gets deselected. Argh